Air pollution exposure 'increases autism risk'

Early life exposure to air pollution from road transport and power plants could increase the chances of a child developing autism. A new study has suggested that exposure to high levels of air pollution during a child's early life could affect the brain growth, increasing the likelihood of developing the mental condition.

Research published in the journal 'Environmental Health Perspectives' looked at the effects of exposure to air pollution in mice. Scientists from the University of Rochester Medical Centre, New York, US, found that exposing young mice to airborne pollutants caused an area of the animals' brains to grow enlarged. Within humans, the enlargement of this area of the brain is found in those diagnosed with schizophrenia and autism.

It was found that the young mice that were exposed to air pollution levels that are typical of a mid-sized US city at rush hour experienced swelling in the lateral ventricles. These areas are chambers on both sides of the brain, which contain cerebrospinal fluid. This swelling resulted in permanent damage to that area of the brain, stopping it from developing any further and the ventricles filling the space that should be filled by the brain as it grows.

It was found that the changes in the brains of the mice were most prominent in males, which is the same as autism and schizophrenia within humans.

Following the exposure to air pollution, the mice underwent short-term memory and learning ability tests. The mice performed poorly in these tests and were also found to have high levels of neurotransmitter glutamate within their brains. This substance is also found in the brains of humans with schizophrenia and autism.

It isn't yet known what causes autism within humans, however; this study follows on from previous research that links air quality to the condition. A previous study performed last year suggested that children that live in close proximity to roads during the first twelve months of their lives were three-times more likely to develop autism.   

Further research is still needed to prove conclusively that air pollution is linked to the development of autism in humans.